Figures & data
Figure 1. Effects of different melatonin concentrations on grape seedling morphology under saline and alkaline stress. M0, control; M50, saline and alkaline stress +50 μmol/L MT; M100, saline and alkaline stress +100 μmol/L MT; M150, saline and alkaline stress +150 μmol/L MT; M200, saline and alkaline stress +200 μmol/L MT. 6 d,12 d, and 18 d indicates processing time. The same as below. The scale in the diagram is 20 cm.
Figure 2. Effects of different concentrations of melatonin on grape seedling biomass under saline and alkaline stress. (a) Roots fresh weight. (b) Roots dry weight. (c) Stems fresh weight. (d) Stems dry weight. (e) Leaves fresh weight. (f) Leaves dry weight. Values represent mean ± standard deviation (n = 3). The graph shows data as mean + standard error of three replicates, significant differences compared with M0 were detected using two-way ANOVA. * denotes significant difference at 0.05 level, **denotes significant difference at 0.01 level, ***denotes significant difference at 0.001 level, ****denotes significant difference at 0.0001 level and no significant difference among the rest of the treatments.
Figure 3. Effect of melatonin on photosynthetic pigments in grape leaves under saline and alkaline stress. (a) Chlorophyll a. (b) Chlorophyll b. (c) Carotenoids. (d) Total chlorophyll. Values represent mean ± standard deviation (n = 3). Significant differences compared with M0 were detected using two-way ANOVA. * denotes significant difference at 0.05 level, and no significant difference among the rest of the treatments.
Figure 4. Effect of melatonin on root activity of grape seedlings under saline and alkaline stress. Values represent mean ± standard deviation (n = 3). Significant differences compared with M0 were detected using two-way ANOVA. ***denotes significant difference at 0.001 level, ****denotes significant difference at 0.0001 level and no significant difference among the rest of the treatments.
Figure 5. Effect of exogenous melatonin on MDA and reactive oxygen species in grape seedlings under saline and alkaline stress. (a) Leaves MDA content. (b) root MDA content. (c) Leaves H2O2 content. (d) Root H2O2 content. (e) Leaves O2−content. (f) Root O2− content. Values represent mean ± standard deviation (n = 3). Significant differences compared with M0 were detected using two-way ANOVA. * denotes significant difference at 0.05 level, **denotes significant difference at 0.01 level, *** denotes significant difference at 0.001 level, ****denotes significant difference at 0.0001 level and no significant difference among the rest of the treatments.
Figure 6. Effect of exogenous melatonin on antioxidant enzymes in grape seedlings under saline and alkaline stress. (a) Leaves superoxide dismutase activity. (b) Leaves peroxidase activity. (c) Roots superoxide dismutase activity. (d) Roots peroxidase activity. Values represent mean ± standard deviation (n = 3). Significant differences compared with M0 were detected using two-way ANOVA. * denotes significant difference at 0.05 level, **** denotes significant difference at 0.0001 level and no significant difference among the rest of the treatments.
Figure 7. Effect of exogenous melatonin on osmoregulatory substances in grape seedlings under saline stress. (a) Leaves soluble sugar content. (b) Root soluble sugar content. (c) Leaves soluble protein content. (d) Root soluble protein content. (e) Leaves proline content. (f) Root proline content. Values represent mean ± standard deviation (n = 3).
Figure 8. Effect of exogenous melatonin on ascorbic acid and glutathione in grape seedlings under saline and alkaline stress. (a) Leaves ascorbic acid content. (b) Roots ascorbic acid content. (c) Leaves glutathione content. (d) Roots glutathione content. Values represent mean ± standard deviation (n = 3).
Figure 9. Diagrammatic representation of the defense mechanisms of grape seedlings against saline and alkaline stress.
